Benefits of ZooKeeper
ZooKeeper is a great choice for high availability application coordination. It’s been battle tested and has a mature feature set. There is a large support base for ZooKeeper. ZooKeeper SDK is available for most programming languages. There is extensive documentation and mailing list detail on every nuance of ZooKeeper. And finally, the codebase is open source. You can see under the hood of the source code and understand how it works.
Etcd is a close competitor to ZooKeeper. Etcd is a younger project, but is rapidly gaining adoption. Projects like Kubernetes and others offer Etcd as the default option. Etcd is a bit easier to use, but doesn’t have all the features that ZooKeeper has.